Just by comparing the pics of the runners, it looks like frame 2 lacks certain parts in the shoulders and feet that are otherwise supplied by parts dedicated to specific designs, judging by the Kimaris frame set. It really just looks like they took frame 1 and cleaned it up by putting the universal parts all on one runner instead of having it spread across one full runner and a smaller, modular one.

I wonder how the Gusion Rebake is going to be handled? Most of its parts are just reused from the Barbatos, so they might use frame 1 again, unless frame 2 is supposed to be a successor.

"For who would lose, though full of pain, this intellectual being--those thoughts that wander through eternity; to perish rather, swallowed up and lost in the wide womb of uncreated night, devoid of sense and motion?"

Now that I've built the Barbatos Forms 4 and 6 and the Gusion Rebake, I have no idea what Bandai's at with these frames. They're constantly using a lot universal parts, like the torso and legs, but they're constantly remolding the parts and frankly wasting a lot of engineering when they could be making use of switches, like the ones built into Frame 2. Then you've got the Frame 4 from Barbatos Form 6, which in all honesty seems like it's supposed to be a truly universal one; it features a lot of switches that Frames 1 through 3 lack, as well as a redesigned shoulder bit that allows it to mount a wider variety of shoulder frames.

Then you come to Frame 3. This one features no switches, but everything but the arms is identical to what you get on Frame 1. Instead it uses those shoulder joints like we've seen in the HG Revive stuff, where the armor itself is the shoulder joint. Just watch, the Astaroth is going to be released with a Frame 5 for some godforsaken reason.

If you're looking at the differences in frames to determine what has the greatest versatility right out of the box, go with the Barbatos Form 6. (The kit also allows you to mostly build a Form 4, just no mace, sword, or plain forearms--but those autocannons are just so cool.)

"For who would lose, though full of pain, this intellectual being--those thoughts that wander through eternity; to perish rather, swallowed up and lost in the wide womb of uncreated night, devoid of sense and motion?"